put 3x=t

3dx=dt

=1/3 ln(sect+tant)

since temperature is const. change in int.energy is 0 hence dq/dv=0

dq=dv+w since dv=0 dq/w=1

  =

let motor boat reach a point B  then return  and  pass the raft at point C after a time t 

AD+BC=AB-AC                                D be the point down stream where AD is the distance travelled in 1hr

by solving above  equations we get t=1hr

for AC (V_r)(1+1)=6  V_r=3kmph

but beta rays are emiited from nucleus

during radioactive  decay  we find the loss of protons but what happens to electrons they should not be lost because air is a bad conductor of electricity

A thin non conducting ring  of radius R has linear charge density has given above where the given angle is azimithul angle find the magnitude of electric field strength on the axis of the ring as a function of the distance x from the centre (x<<R)